Production of glycerin by fermentation



UNITED STATES PATENT OFF-ICE.

ALLEN T. COOKING, OF SUTTON COLDFIELD, AND CECIL H. LILLY, OF BIRMINGHAM,

' ENGLAND.

PRODUCTION OF GLYCERIN BY FERMENTATION.

No Drawing.

Toe whom, if may concern Be it known that we, ALLEN THoMAs CooKiNe, a subject of the King of Great Britain and Ireland, and residing at Carhalnpton House, Four Oaks, field, in the county of Varwick. E and CECIL I'lnnnrurr LILLY, a subject of the King of Great Britain and Ireland, and residing at 29 Carlyle Road, Edgbaston, Birmingham, in the county of \Varwick, England, have invented certain new and useful Improvements in the Production of Glycerin by Fermentation, of which the following is a specification.

This invention relates to the production of glycerin by fermentation.

It is. known that sugars can be fermented with the production of alcohol and glycerin, and among the objects of the present invention are to obtain increased yields of glycerin, and to reduce the time factor of the fermentation.

It has hitherto been thought necessary to employ large additions of alkaline salts to the mash in order to obtain good yields of glycerin, and that within certain limits the greater the amount of alkaline salt added, the higher the yield, but we have found. that alkaline additions are unnecessary and have substantial disadvantages.

The production of glycerin by fermentation in the presence of normal sulphites, as has been proposed, depends upon the fixation of an intermediate product of alcohol fermentation, viz, acetaldehyde, and upon the aifinity of acetaldehyde for bisulphites.

Now although bisulphites are relatively strong antiseptics and cannot be used alone in large quantities so that-it has been believed necessary to allow the bisulphite to be produced by the reaction and taken up at once by the acetaldehyde, we have discovered that they may be used in conjunction with normal sulphites producing a mixture which in solution is relatively non-antiseptic and neutral in reaction to litmus. The use of the mixed sulphites has substantial advantages, for example, the presence of the bisulphite anticipates the eventual splitting up of the normal sulphites in fermenting liquors, resulting in the fixation of the acetaldehyde at an earlier stage and consequently the saving of a portion of the sugar which with normalsulphites alone would pass completely through the various stages Specification of Letters Patent.

Sutton Cold ngland,

Patented Aug. 15, 1922.

Application filed August 23, 1920. Serial No. 405,300.

of fermentation to alcohol before suflicient bisulphite could be formed for fixing the intermediate product, acetaldehyde. Thus with normal sodium sulphite alone, the following reaction would take place the reaction with the saltsmixed in equal proportions being Again in such fermentations the alkalinity resulting from the splitting up of the sodium sulphite can be reduced to a min imum, or may be entirely eliminated by adding bisulphite or increasing the proportion of bisulphite to normal sulphite in the subsequent additions, so as to neutralize the bi carbonate formed, thus, the reaction when using normal sulphite alone is as follows 2NaHSO +2NaHCO the reaction with a mixture of the salts in molecular proportions being 00, H2O NaHSO, na so V znanso, NaHOO showing that with the normal sulphite, 252 parts will produce 168 parts of bicarbonate,

whereas with the mixed salts, 230 parts of the. mixed sulphites produces only 84 parts of bicarbonate.

We find that most yeasts can be employed without special precautions being taken to acclimatize them to the special conditions.

We also find that for the same glycerinand bisulphite of an alkali metal as will produce a mixture of mash and salts which 18 approxlmately neutral to litmus.

The invention also consists in the production of glycerin by the fermentation of fermentable sugars with yeast by the addition to the sugar solution of such mixtures of sodium sulphite and sodium bisulphite as do no inhibit fermentation.

The invention further consists in adding mixtures of sulphites (preferably in solution v ther 1 1b. at 26 hours.

in water) in successive small proportions, until an amount has combined with the acetaldehyde corresponding to the yield of glycerin required, having regard to the other by-products which may be desired. or until the amount of sulphites practically required for the production of the corresponding theoretical yield of glycerin is --reached. (The theoretical quantity of sulphitecalculated as Na SO -corresponds, we find, to 70% of the weight of the fermentable sugar; the theoretical yield of glycerin then amounting to 50% of the fermentable sugar; but the amount practically required may amount to 30%). It will; ofcourse. be understood that the amount of normal sultite added must eventually be sufficient to combine with the amount of aldehyde to be formed during the fermentation process.

The invention also consists in adding water solutions of sodium bisulphite the fermentation proceeds, or increasing the proportion of sodium bisulphite in the mixture additions to maintain approximate neu trality to litmus. I

In carrying the invention into effect according to one example, we take 15 gallons of an aqueous solution of molasses or sugar, containing 10.5% of total fermentable sugars and the yeast culture, and we. add to this an aqueous solution containing 5 lbs. of a mixture of Na SO and NaHSO, in equal proportions to produce a solution having the reaction neutral to litmus. After 18 hours of fermentation we add a further 2 lbs. of

the mixed sulphites previously dissolved in a portion of the fermenting liquor, this op eration being repeated with 1 lb. of the mixed salts-added at 24 hours, and a fur- 86% of the sugars present are in this case consumed in 120 hours from the'commencement of the operation, and the yield of glycerin calculated on the sugar consumed amounts to about 35%%, the average temperature throughout being 36 C.

. In the above case the commercial sulphite mixture added contained the equivalent of 90% as Na SO so that in all 9 lbs. of the mixed commercialsulphites containing actually 8.1 lbsJof mixed sulphites was added.

At the end of the above period, the solution contained 0.9% of uncombined Na SO,,, and 1.5% of unfermented sugar, so that 6.8 lbs.

of Na SO hadcombined in the reaction,

whilst 13.7lbs. of sugar hadbeen fermented. The calculated yield of glycerin on the sulphite combined is equivalent to 4.89 lbs. of

glycerin on 13.7 lbs. of sugar consumed, or 35.6%. Actual analysis gave a figure of 35.5%. The ratio of sugar to sulphite added was 100250, whilst the ratio of sugar con sumed to sulphite combined was 100:49.6. The theoretical proportions for the maximum theoretical yield of glycerin, i. e. 50% on the sugar consumed, are 100 70. By our method it is unnecessary to add the sulphite in quantities exceeding toany great extent those theoretically required; nevertheless it is desirable to add up to about 10% in excess of the theoretical requirements, and the yields of glycerin and other products can be regulated as desired.

lVe further have found that it is better to dissolve the mixed salts to be added, in water instead of in a portion of the fermenting liquor as the time required for completion of the fermentation is thus reduced and injury to the cultures is avoided.

By increasing the total quantity of sulphites added, and continuing the fermentation, the yield of glycerin and acetaldehyde can be increased up to approximately 50% of glycerin expressed on the sugar consumed. with the production of relatively less alcohol.

The avoidance of additions of sulphites in large excess has the advantage that the working up of the fermenting liquors is considerably facilitated.

A substantial advantage of this process is the freedomof choice it confers on the user in regard to the relative proportions of the principal products obtained, i. e., glycerin, acetaldehyde and alcohol. In some circumstances, e. g. it will be desirable to produce less glycerin and acetaldehyde and more alcohol.

In order to illustrate the flexibility of the process in this respect we give three further examples:

(a) lVhere the maximum glycerin yield is desired;

(6) Where a smaller yield of glycerin and a higher yield-of alcohol is desired;

(0) Where a still smaller yield of glycerin and a still higher yield ofalcohol is desired.

E mample (a).

311 gallons of a solution of crude cane sugar equivalent to 788 lbs. of glucose (23.8% on solution) were' sterilized and 4:0 lbs. of pressed yeast added. At intervals extending over a period of five days when the: fermentation was most vigorous Was added asolution in water of a mixture of sodium sulphite (95% N a 50,) and sodium bisulphite (95% NaHSO in equal parts by contaihing 545 lbs. of Na SO wereadded and theanamese added. In-all, and'extending over theperiod mentioned above, 176 gallons of water the mixed salts equivalent to fermentation was allowed to complete itself for afurther four days at a temperature:

of 35 C. to 37 C. y 1

Therefore 788 lbs. of sugar in 487 of liquidis equivalent to an initial sugar concentration of 16.1%. After nine days 95% of the ori' sumed while su phite equivalent to 39 lbs.

of Na SO remained in the solution uncom bined. Therefore 749 lbs. of sugar during fermentation had fixed au antity of salts equivalent to 506 lbs. of Na 0,. This quantity of Na,SO is equivalent to a production of 364 lbs. of glycerin or 48.6% of the weight of sugar consume-d. Actually 336 lbs. of glycerin were found by analysis or calculated on the weight of sugar consumed'. The acetaldehyde produced in this 'case is equivalent to 23%ofthe sugar consumed, viz, 172.2 lbs.

while the alcohol amounts only to 5% of the sugar consumed,

viz, 37.4 lbs,

' Ewample (,b)

412 gallons of solution of crudecane sugar equivalent to 830 lbs. of glucose (20.1% on solution) were sterlized, and 40 lbs. of pressed yeast added.. At intervals extending over a period of three days,when the fermentation was mostvigorous was added a solution in water of a mixture of sodium sulphite (95%) and sodium bisulphite (95%) in equal parts by weight, WhlCh solution was neutral in reaction to. litmus- At first 66 lbs of the mixed Salts in 24 gallons of water. were added each time, but later'this was reduced to 33 lbs. of mi ed salts in the' ame volume of water per a dition,

\ In all, and extending over the period mentioned above 232 gallonsof water containing the mixed salts equivalent to 511 lbs. of. Na SO were added and the fermentation allowed to complete itself for a further three days at a temperature of35 C. to 37 C.

, 5 Therefore 830 lbs. of sugar. in 644 gallons of liquid is equivalent to an initial sugar concentration of 12.8%. I

After a period of six days from the commencement of the fermentation 98.4% v of the' S11 M had been consumed,*wl1'ile salts equiva fixed a, uantity of salts equivalent to 486' lbs. of a 80,. This quantit of Na SO is equivalent to a production 0 349.9 lbs. of

lycerin of 41.6% on the sugar consumed ictually 351 lbs.of glycerin were foundby v analysis or 43% calculated on" thesugar consumed.

The acetaldehydeproduced in thls case isv equivalent. to 21% of ithe sugar consumed, or

145 gallons of a solution of gallons",

inal sugar had been consolution.

fixed a quantity of salts equivalent to 93 lbs. of Na SO,, equivalent to a production tation.

cut to 25 lb's.'.of Na SO remained uncombined; therefore 816.7 lbs.of sugar had 171.5 lbs. while. the alcoholamolintsof 8% or 65.3 lbs. of the sugar consumed.

' Example (0).

sugar equivalent to 288 lbs. 19.8% on solution)"'were sterilized and added to the culture remainin in the fermentation vat from a previous ermentation. At intervals ex ing over two days, when the fermentation was most vigorous, was

crude caneof glucose added a solution in water of sodium sulphite 595% Na SO and sodium bisulphite 95% NaHSO in equal parts by weight,

which solution was neutral in reaction to litmus. 12 lb. quantities ot-the mixed salts in 8 gallons of water were added eachtime,

the total additions amounting to 76 gallons of water containin mixed salts equivalent to 93 lbs. of Na,S At the end of four.

days at a temperature of 35 C. fermentation had ceased. 288 lbs. of sugar in. 221gallons of liquid is equivalent to an initial sugar concentration of 13%. When fermentation has ceased 97% of the sugar had been .con-' sumed, while no free sulphite remained in Therefore280 lbs. of sugar had of 66.9 lbs. of glycerin or 23% on the sugar consumedl Actuallyv 70.8 lbs. of glycerin.

.mentation bya yeast ofa-solution containv ing a.-*fermentable .sugar with such propor-* tions of normal sulphite and bisulphite of' an alkali metalaswill produce a mixture of mash and salts which is approximately neu tral to litmus. a

2. A process which consists in the fermentation by a yeast of a solution containing a fermentable sugar with such proportions of sodiumsulphite and sodium bisulphite as will produce a mixture of mashand salts which is approximately neutral/to litmus.

'3. In a process which consists in the fermentation by a yeast of a solution contain ing a fermentable'sugar the addition in successive small portions of a mixture of normal sulphite arid bisulphite of an alkali meta-l until an amount has combined with the acetaldehyde corrmponding to the other by-products desirgd, the proportions of normal-sulphite and bisulphite being such as to maintain the mash approximately neutral to litmus. I 4. In a process consisting in the fermentafi tion by a; yeast of a solution containing a ro mixture of mash and salts approximately neutral to "litmus.

5. In a process consisting in the fermenta- .tion by a yeastof a s olution containing a fermentable sugar the addition in successive small portions of a solution containing normal sulphite and bisulphite of sodium in such proportions as will produce a mixture of mash and salts approximately neutral to a, litmus. 20

' 6. A- process whichconsists inthe -fer mentation by yeast of a solution containing a :fermentable sugar in-the: presence of a normal sulphite and bisulphlte of an alkali netal in such proportions as will produce a solution approximatel --ne utral to litmus including the step of a ding an aqueous=$olution' of the bisulphite of the alkali metal as the fermentation proceeds.

7-. A process as. claimed in claim 6 in which the addition of the bisulphite is made a mixture of normalsulphite and bisulmea est S. phite, the p gportion of bisulph teun the neutral to litmus.

I 8; A process as claimed in claim, 1 in I l which the sulphite and bisulphite are employed in 'eq -ual proportions L 9. Thec process which consists in the addi-. tion to an aqueous solution of sugar an ye ast.of amixture of equal parts 01" sodium sulphite and sodium bisulphite in the relative proportions 5 lbs. of'mixture to 15 gal- I lons of solution containing 10.5 per cent of the total fermentable sugars and yeast; the addition after an'interval of a further quan-' tity ofi dissolved mixed sulphites in the proportion of 2 lbs. for the quantities given above, the further addition of another quan tity of mixed salts after another interval of fermentation'jin the proportion of 1 lb. for the above quantities and the still further addition of a guantit equalto the last quantity of mixedsulp ite and b'isulphite after a further period.

In testimony whereof we have signed our names to this specification a 'll. COCKING. 0, H; LILLY. 

